GGSPro Tech Tips

Catch-22 for Herbs and Pesticides: Best Practices to Minimize Pesticide Use

Herbs grown today can be used by consumers in several ways including ornamental plants, for medicinal and culinary purposes, and for homemade items like potpourri. The idea that herbs are pest-free is a common consumer perception but, regrettably, not true.

Very few pesticides on the market are registered for use on all herbs, so scouting is essential for early detection of pests. The best way to manage pests is to place emphasis on IPM practices. With proper planning and implementation, pest detection and establishing thresholds for action can be achieved.

Insect Control Implementation

Examining a sticky card with a hand lens
Yellow sticky cards, placed vertically with one-third in the plant canopy, will attract flying insects such as winged aphids, fungus gnats, shoreflies, thrips and whiteflies. The “beat test” can be used to dislodge pest from plants to provide an overview of pest presence. A hand lens or optivisor can be used to identify smaller insects not detectable on sticky cards such as spider mites, soft scales or mealybugs. Examine the undersides of the leaves and along leaf veins for presence of eggs or immature nymphs. Be observant of sticky substances on leaf surfaces, known as honeydew, that are secreted by aphids, mealybugs and soft-scale insects. Ants may also be present and will actually defend these colonies.

If you want to stay on top of pest problems, learn to recognize symptoms or signs of pest
activity as well as the presence of beneficial organisms. A symptom is evidence of activity such as holes in a leaf or a wilting leaf. A sign is evidence of an organism causing the damage such an aphid shed skin or mycelium growing on a leaf surface.
Brown marmorated eggs 
and hatching nymphs

If growing herbs outdoors, utilize the growing degree day (GDD) to determine insect emergence times. Grower degree days are a measure of accumulated heat. Growers and landscape technicians can use this measurement of heat to predict which insects will be active at which point, in order to improve pesticide application efficacy and reduce pesticide use.

Row covers placed over plants serve to protect them from harsh weather conditions as well as limit insect, disease and other pests. Trap plants are used in luring pests away from the main plant during critical times. Trap crops can be paced around the perimeter of the crop to be protected or within the crop, depending on the pest to be trapped. Examples of trap crops includes nasturtium to attract aphids, basil and marigold to attract thrips, or chervil to attract slugs.

Companion plants such as marigolds, sweet alyssum, cosmos and caraway can also attract beneficial predator insects to aid in controlling pests. Biocontrol of insects and mites is becoming an increasingly popular way to manage these pests. Contact the GGSPro team for assistance in implementing a biocontrol plan for herbs.

If chemical control is needed, choose soft or reduced-risk pesticides, referred to as biorational pesticides. Most herb growers look for products that are OMRI-certified and have zero-day or short pre-harvest intervals (PHI). Griffin offers products such as insecticidal soap, horticultural oil, neem/azadirachtin insect growth regulators and microbial products labeled for herbs. GGSPro has written a bulletin titled, “Pesticides Labeled for Herbs” that’s a useful guide for herb growers. The bulletin is free upon request. It is the grower’s responsibility to read and follow the entire pesticide label, including checking to be sure the herb you wish to treat appears on the label.

Insecticidal soap and horticultural oils rely on thorough coverage for success. These products provide a quick knockdown but have no residual control. Applications using soaps or oils should be made when conditions are good for drying (clear, sunny days) and air temperatures are between 40-80oF.

Insect growth regulators are often tank-mixed with other pesticides to help inhibit or interfere with part of an insect’s life cycle. A common example allowed for greenhouse herbs would be azadirachtin, found in Molt-X, AzaGuard or Azatin O for use on aphids, thrips and whitefly control. Specifically in aphid control, it works by preventing the molting process of the aphid, where the old skin is shed to allow a new one as the insect grows. These products do not control adult pests.

Microbial products can be a bacterium, such as in DiPel, which specifically targets worm (lepidopteran) larvae. Grandevo PTO is another bacteria-based product, with broad activity against insects and mites. Fungal microbial insecticides that target many soft-body insects include Botanigard/Mycotrol/BioCeres and Preferal. Repeated applications are recommended along with a high humidity requirement to aid in these fungal spores surviving while they germinate and penetrate into the insect’s exoskeleton to cause insect mortality. Broader chemical control options include Conserve (outside herbs only), Entrust SC, and Pyganic 5.0.

Disease Control Implementation

Preventing diseases should be proactive rather than reactive. Knowledge of the disease pathogens most prevalent in herb production is a good place to start. The most common disease issues include Botrytis, powdery and downy mildew, Alternaria leaf spot and damping-off diseases caused by Pythiumor Rhizoctonia. Good cultural practices include avoiding high-density planting and extended leaf wetness while providing good air movement. Taken together, these steps reduce humidity and therefore foliar disease occurrence.

Botrytis spores and stem canker on basil
Scouting is just as important for diseases as it is for insects and mites. It’s important to examine the root system for evidence of healthy, white roots. Biofungicides such as Rootshield, Cease, Companion and Triathlon BA applied as soil drenches aid in protecting roots against root pathogens and may also reduce the need for foliar fungicides. Damping off can cause seeds to fail to germinate, or it may cause them to succumb to a stem canker that girdles the stem.

Visible spores may or not be present on leaf or stem surfaces. Botrytis will appear as fuzzy gray-colored spores. Botrytissporulation increases significantly during humid, overcast weather conditions. Biofungicides such as Cease, Companion or Triathlon BA as well as traditional fungicides such as ZeroTol or Heritage can be applied if symptoms are observed.
Selecting herb varieties with disease resistance, especially to powdery and downy mildews, offers reliable protection while not compromising flavor or appearance.

Bacterial infections appear as water-soaked brown or black greasy looking spots which may be surrounded by a yellow halo when they occur on the foliage. In some cases, bacteria may be carried in the seed coat, especially on vegetables. Purchasing treated seeds where available may help eradicate infections. Bacterial infections require the pathogen inoculum, a susceptible host plant and wet conditions. Bactericides required to treat bacterial infections are limited and labels must list the herb being treated. Camelot O and Phyton 35 are labeled for several herbs, but not all.
Bacterial leaf spot on cilantro

Increase plant defenses against foliar pathogens by using the microbial biofungicides Regalia PTO, Fosphite and Alude. Essential Organic 1-0-1 is a root and plant stimulator that contains multiple beneficial active ingredients including kelp. Sil-Guard (0-2-5) contains potassium silicate to aid in strengthening plant cell walls and stem strength to aid in reducing stress to environmental conditions. 
Fungicide ProductsDescriptionItem Number
Alude2.5 Gal71-27601
Camelot1 gal70-21201
Cease1 gal71-13301
Companion1 gal71-1375
Fosphite EC1 gal71-1520
Heritage4 oz71-1404
Regalia PTO1 gal70-2850
Rootshield WP10 lb71-2789
Triathlon BA1 gal71-3040
Insecticide ProductsDescriptionItem Number
AzaGuard EC1 qt70-1224
Azatin O1 qt70-12301
BioCeres WP1 lb70-1245
BotaniGard ES1 qt70-12501
BotaniGard Maxx1 qt70-1253
BotaniGard WP1 lb70-12521
DiPel Pro1 lb70-1450
Entrust SC1 qt70-1538
Grandevo PTO5 lb70-1760
M-Pede2.5 gal75-10262
Mycotrol WPO1 lb70-2420
Preferal1 lb70-2650
Pyganic 5.0 Speciality1 qt70-2687
Ultra-Pure Oil2.5 gal70-21401
Plant StimulatorsDescriptionItem Number
Essential Organic 1-0-11 qt166003GR
Sil-Guard2.5 gal16GP501821
Row CoversDescriptionItem Number
15' x 300'DuPont 1.25 oz78-2045
50'-500'DuPont 15' width78-2005
50'-500'DuPont 30' width78-2010
50'-500'DuPont 45' width78-2015
50'-500'DuPont 60' width78-2020

The Plants Strike Back: A SAR Wars Story

Plants have defense systems that are activated when a plant is infected by a pathogen or suffers insect damage. The attack on the plant sets off a signal, which is carried through the plant in the form of a small molecule such as salicylic acid, jasmonic acid or ethylene, for example.

The exact chemical signal is dependent upon the plant type and the nature of the attack. Is it an insect or a pathogen? Is it a pathogen which kills plant tissue such as Pythium or Fusarium, or a foliar infection like rust or powdery mildew? The answer determines which chemical signal is sent, and initiates a cascade of biochemical reactions within the plant, which can be quite wide-ranging. For example, the plant may produce an elevated level of antifungal proteins, or reinforce its cell walls with cellulose, lignin and proteins.

Systemic Acquired Resistance (SAR) is like the immune system of a plant. A number of plant-protection and fertilizer products can trigger the signals of the SAR pathways in plants.
The observable effect of this chemical signal is termed Systemic Acquired Resistance (SAR). Think of SAR as the immune system of a plant; it’s comparable to our own immune systems in that the immunity or resistance generated may be long- or short-lived, and the degree of resistance will vary by organism being presented.

A number of plant-protection and fertilizer products can trigger the signals of the SAR pathways in plants. These products range from small molecules to living organisms. The defense signal(s) can be elicited by small molecules such as potassium phosphite, thiamine or potassium silicate.

Potassium phosphite fungicides such as Fosphite and Alude have undergone the rigorous testing required of registered fungicides (as well as the test of time). They’re well-known for their efficacy in preventing Pythiumand Phytophthora, and for stimulating root growth. In part, the activity is due to induced resistance by the phosphite.
Geranium (shown above) is among several crops that
can be sensitive to excess silicate. Others include
begonia, gerbera, pansy, petunia and tomato.

Thiamine, or vitamin B1, is also capable of inducing a SAR signal. Thiamine is just one of many plant-boosting ingredients in the nutritional supplement Essential Organic 1-0-1 (formerly called Essential Plus). Potassium silicate and potassium phosphite are supplied in SilGuard (0-2-5). Silicate, phosphite and salicylic acid – all three – are provided in the supplement SiTKO SA 0-7-17. Some common bedding plants can be sensitive to excess silicate including begonia, geranium, gerbera, pansy, petunia and tomato, so it’s important to observe label rates and precautions.

More complex natural products such as extracts of kelp, algae or certain terrestrial plants, as well as biochar (created by pyrolysis of wood or other plant material) have been shown to improve crop performance. The improvement seen is, in part, due to the ability of the materials to induce resistance signaling in the plants, along with any nutritional benefit, of course. Kelp extracts can be found in Growth Products’ Essential Organic 1-0-1, a root and plant stimulator product. Essential Organic is a complex product combining many beneficial ingredients for plant health, in addition to those that may elicit resistance.

Another professional product based on plant extracts is Regalia PTO fungicide. Regalia is derived from extracts of the giant knot weed, Reynoutria sachalinensis. Regalia PTO has been shown to protect plants through induced resistance. It’s effective against a large number of fungal and bacterial pathogens, and can be used as a spray or a drench.

Even more complex interactions occur between plants and the living bacteria and fungi we use as plant protectants including Bacillus species, Trichoderma species, mycorrhizae mixes and others. Companion, Cease, Triathlon BA, RootShield and RootShield Plus are all registered fungicides which utilize microbe-to-plant interactions to protect the plant from infection. Products based on Bacillus bacterial strains provide root and foliar protections due to multiple mechanisms, at least one of which is induction of the plants’ own resistance pathways. Bacillus fungicidal products include Companion, Cease and Triathlon BA. Similarly, the RootShield products, based on a Trichodermafungus, are used for protection against root rots, and they’ve also been shown to reduce the need for foliar fungicide applications.

Griffin has recently added biological soil supplements by Nature’s Source to our product offering. Plant Probiotic and Biotik products both combine Bacillus, Trichoderma and other organisms in a soil amendment aimed at growth stimulation. These multi-microbial formulations aid in nutrient uptake and reduce plant stress, in part at least, by inducing the resistance system within the plant.

Multi-microbial formulations, as found in Plant Probiotic and Biotik, aid in nutrient uptake and reduce plant stress. This happens, at least in part, by inducing the resistance system within the plant.

This is similar to the beneficial effects of mycorrhizae, which colonize the root systems of up to 80% of all plant species in nature. Endomycorrhizae colonize inside of the root cells and are most prevalent, while ectomycorrhizae are associated with the root surface and are most prevalent in interaction with hardwood and conifer trees. The organisms form threadlike chains that function as extensions of the root, delivering water and mineral nutrients to the plant. In the symbiotic relationship that occurs, the plant feeds the mycorrhizae with sugars and more complex nutrients. Observed benefits include improved plant health and more efficient nutrient usage, both of which may lower the costs for fertilizer and fungicides.

Mycorrhizae organisms won’t colonize all plant species equally and mycorrhizae products should be an appropriate mix for the plants being inoculated. A new line of mycorrhizae products, called MycoApply, is set to come to market – and to the Griffin product portfolio – soon. MycoApply products are based primarily on members of the Glomus genus, and multiple formulations will be available for growers to choose from.

Analogous to vaccines and human immunity, products which utilize induced resistance should be thought of as preventative, reducing the overall need for curative actions and improving plant health. Many of these products work by multiple mechanisms, and in ways researchers are still striving to understand. However, taking advantage of the current knowledge and tapping into the plants’ ability to launch a defense can benefit your growing operation with healthier plants and reduced usage, and therefore longer lifetimes, of chemical fungicides.
ProductsDescriptionItem Number
Alude2.5 gal71-27601
Cease1 gal71-13301
Companion1 gal71-1375
Essential Organic 1-0-11 qt166003GR
Fosphate1 gal71-1520
MycoApplyNAComing Soon
Plant Biotik5 lbs67-0071
Plant Probiotic5 lbs67-0070
Regalia PTO1 gal70-2850
RootShield10 lbs71-2780
RootShield Plus10 lbs71-27911
SilGuard2.5 gal16GP501821
SiTKO 0-7-172.5 gal16GP30053
Triathlon BA1 gal71-3040

A Perennial Cover Story: How to Manage Temperature in Outdoor Production

What to do… cover or uncover?

Outdoor perennial production is subject to all of the natural elements and, just like the weather itself, doesn’t follow a specific set of rules. The main goal is to avoid extreme temperature fluctuations. Perennials that are warmed too much become more sensitive to cold nighttime temperatures, and more susceptible to cold damage. Keep temperature swings in check by preventing daytime temperatures from heating up your perennial crops. Let the weather report be your guide; closely monitor the forecast to help you determine when to remove or reapply coverings to your crop.

Perennials that are warmed too much become more sensitive to cold nighttime temperatures, and more susceptible to cold damage.

When outside temperatures begin to rise above 40°F and new plant growth starts to develop, ventilate the hoop house or uncover the beds to promote air circulation. Doing so ensures that new growth doesn’t stretch or become soft. Avoiding heat build-up on sunny winter days is very important!

Greenhouses with roll-up sides are ideal to maintain cool temperatures if outside temperatures rise above freezing. White poly and/or positive ventilation can also be used to keep daytime air temperatures cool. The “winter protection fabric” from Griffin comes in 12’ and 15’ widths; it’s a convenient way to cover and uncover your perennials. Once warm weather arrives in the spring and remains above freezing for a period of time, removal of the thermal blanket coverings and white hoop house poly can be permanent. When you’re done with them for the season, let them dry, fold them up and store them for next season. 

Experience teaches: “When in doubt, keep them covered.”

Alyssum Summit Golden Yellow
Photo courtesy of Syngenta Flowers, Inc.
After uncovering, it’s important to address any decayed or damaged plant material that resulted from overwintering. Thorough cleanup is key to preventing problematic foliar diseases including Botrytis, powdery mildew, rust and downy mildew. Broad-spectrum fungicide sprays such as Affirm, Mural, Orkestra Intrinsic, Pageant Intrinsic or Palladium are helpful in preventing these foliage diseases, too. Specifically for outdoor use, Concert II is another good broad-spectrum option.

A preventative broad-spectrum fungicide drench can also be applied to add extra protection from root, stem and crown diseases. Banrot, Segway, Terrazole or Truban are recommended options to keep Pythium at bay. To prevent Rhizoctonia, consider Cleary’s 3336, Emblem or Medallion.

ProductsDescriptionitem Number
Affirm WDG0.5 lb71-1129
Banrot 40 WP2 lb71-1210
Cleary's 3336 EG5 lb71-2550
Concert II2.5 gal71-1365
Emblem1 pt71-1570
Medallion WDG8 oz71-16502
Mural WDG1 lb71-1690
Orkestra Intrinsic16 oz71-2200
Pageant Intrinsic WG1 lb71-26801
Palladium WDG2 lb71-2685
Segway O16 oz71-31101
Terrazole WP2 lb3183862
Truban 30 WP2 lb71-3065
Winter protection fabric6 oz, 12' x 150'81-730200
Winter protection fabric6 oz, 15' x 150'81-730400

New Options for the New Year: New Pesticides Bring Improved Control for Growers

Several new pesticides came to market in late 2016, including two fungicides and one insecticide that bring improved attributes to the table. For growers who are considering the addition of these products to their toolbox for spring 2017, let’s take a closer look at each:

Orkestra Intrinsic, from BASF, combines two active ingredients (AIs) representing modes of action 7 and 11. One active ingredient, pyraclostrobin, has been available to growers in the product Pageant Intrinsic. In addition to being a broad-spectrum preventative strobiluron fungicide, pyraclostrobin has been shown to have many plant health benefits. Tolerance to cold and drought have been documented, as well as faster and better rooting on a wide variety of plant material.

Fluxapyroxad is the other active ingredient; it’s a new AI for greenhouse and nursery growers. It expands the number of diseases controlled, as well as providing knockdown activity for common foliar diseases such as Botrytis and powdery mildew. When applied as a soil drench, fluxapyroxad also adds Thielaviopsis control.

Orkestra Intrinsic is formulated as a liquid suspension concentrate. Foliar sprays control Botrytis, downy mildew and powdery mildew, as well as many leaf spot diseases, crown rots and stem blights.  Soil drenches provide preventative control of Fusarium, Rhizoctonia and Sclerotinia, and suppression of Phytophthora, Pythium and Thielaviopsis.

Impatiens downy mildew
It is labeled for use on ornamental plants in greenhouses, shade houses, lathhouses, outdoor nurseries, retail nurseries and landscapes. Orkestra has a 12-hour REI, making it suitable for inclusion in many disease programs. Registered in all states except California.    

Segovis is a unique new fungicide from Syngenta. Its active ingredient is oxathiapiprolin, designated as mode of action group U15. Segovis brings with it the longest length of residual control of downy mildew on the market when applied as a soil drench—up to 6 weeks depending on the drench rate applied. This is very welcome news to growers producing Impatiens walleriana that are defending their crops from impatiens downy mildew.

Segovis brings the longest length of residual control of downy mildew on the market when applied as a soil drench—up to 6 weeks depending on the drench rate applied.

Segovis is also highly effective against Phytophthora when applied by spray or drench. Aerial Phytophthora has been an in increasing problem for spring petunia growers, especially in the propagation of vegetative cuttings. Best applied preventatively or at the first sign of disease, Segovis is labeled for ornamentals in greenhouses, shade houses, lathhouses, outdoor nurseries and commercial landscapes. Segovis is a good tank-mix partner, has just a 4-hour REI and no signal words on the label. Not registered in New York.
Aerial Phytophthora on vegetative petunia

BotaniGard MAXX from Bioworks is a dual active-ingredient insecticide with the mode of action group 3A. Many growers are familiar with BotaniGard; it utilizes the microbial insecticide Beauveria bassianastrain GHA, which works by germinating on several soft-bodied insects and making penetration, causing death over a period of a few to several days. BotaniGard MAXX adds a second active ingredient, a natural pyrethrin, to add a quick knockdown of several insects. Used as a foliar spray it provides control of aphids, thrips, whitefly, mealybugs, leafhoppers, plants bugs and many more.

Many growers are familiar with BotaniGard. BotaniGard MAXX adds a second active ingredient to add a quick knockdown of several insects.

BotaniGard MAXX is labeled for ornamentals, herbs, vegetables, fruits and nuts in greenhouses, shade houses, nursery, field, landscape, turf and interiorscapes. It has a 4-hour REI, 0-day PHI, excellent plant safety and can be used through a variety of low-volume applicators. Bioworks publishes a compatibility guide to assist with tank mixing. Registered in all states except California.    

ProductDescriptionItem Number
Orkestra Intrinsic16 oz71-2200
Segovis1 pt71-3100
BotaniGard MAXX1 pt70-1253
BotaniGard MAXX1 gal70-1254
BotaniGard MAXX2.5 gal70-1255

Rooting Out Root Rots: How to Defeat Pythium and Phytophthora

Soilborne pathogens cause significant losses to ornamental and vegetable crops in greenhouses and nurseries worldwide. Pythium and Phytophthora are among the most common of these pathogens. Such pathogens are commonly referred to as “water mold” pathogens rather than true fungi because they’re associated with wet conditions, wherein they produce swimming zoospores. These pathogens lead to root and crown rots, and can cause disease if splashed onto plant foliage.

Both Pythium and Phytophthora are natural soil inhabitants and gain access into production areas via irrigation water, soil, airborne spores, insects, weeds, equipment and footwear. They can also carryover in crops harboring the pathogen. 

Pythium root rot on petunia
Pythium is characterized by brown patches on roots. A diagnostic tool for Pythium is the ability to gently slide the outer root tissue off the root, leaving only the inner cortex. Infected plants will generally show mild-to-severe yellowing prior to collapse. Optimum soil temperatures for Pythium vary with the pathogen species: P. aphanidermatum is 95oF, P. irregulare is 86oF and P. ultimum is 76-86oF.

Pythium is an opportunistic disease. It easily spreads through water, and tends to infect plants that are already subject to stress. Fungus gnats are also known to spread Pythium in the greenhouse environment.

Cultural management is key in reducing Pythium risk: Produce crops within their ideal temperature range. Avoid strong wet/dry media moisture cycles. Avoiding excessive fertilization that can contribute to high media-soluble salts (EC). Practice strong sanitation prior to and during crop production. Be sure to filter or treat recirculated water.

Phytophthora root rot and aerial blight on fuchsia

Phytophthora is a fast-moving pathogen. It’s characterized by decline symptoms including leaf yellowing, stunting, wilting and blighting of petioles. This pathogen often leads to plant death in a short period of time. Root symptoms are similar to Pythium except for root sloughing. Examination by cutting into the crown area may reveal a reddish brown discoloration and dark streaks moving up the vascular system.

Phytophthora onset is favored by high soil moisture and warm soil temperatures. Like Pythium, optimum soil temperatures will vary with the Phytophthora species. Phytophthora overwinters in soil/media mainly as dormant resting spores (oospores or chlamydospores).

We're fortunate to have a range of choices, both chemical and biofungicides, labeled to prevent and control Pythium and Phytophthora pathogens.

We’re fortunate to have a range of choices, both chemical and biofungicides, labeled to prevent and control Pythium and Phytophthora pathogens when applied as drenches. Biological fungicides must be applied preventatively as they have no curative properties. These fungicides fit nicely into a traditional IPM program as being compatible with most chemical fungicides if needed. Traditional chemical fungicides may be applied preventatively as well as curatively. All labels must be examined carefully for crops being treated, and for application intervals.

The GGSPro Technical Reference Guide contains important mode of action (MOA) information to help growers make good fungicide rota­tion choices. The GGSPro team is available to answer your inquiries as well. Pesticides other than those mentioned here may also be legal, safe and effective.

Product Description Biological Chemical Ornamental Edible Item no.
Actinovate 18 oz X X X 31007318
2.5 gal
1 gal
X X X 71-27601
Banrot WP 2 lb X X 71-1210
Triathlon BA
1 gal
1 gal
1 gal
X X X 71-13301
Rootshield Plus G
Rootshield Plus WP
1 lb
1 lb
X 71-27911
Segway O 16 oz X X 71-31101
Subdue MAXX 1 qt X X 71-2979
Terrazole L
Terrazole WP
Truban EC
Truban WP
1 qt
2 lb
1 qt
2 lb
X X 71-3025
ZeroTol 2.0 2.5 gal X X X 71-35501

Maintenance Essentials: How to Keep Your Fertilizer Injector in Top Condition

How many times have you heard the statement, “If you take care of your equipment, it’ll last longer?” We can all agree that, eventually, your car will need an oil change, your air conditioner will need refrigerant and your lawnmower blades will need sharpening. Where does your fertilizer injector rank when it comes to maintenance?

Most greenhouse operations deliver the majority of their fertilizer through the irrigation system, making fertilizer injectors essential. An injector that’s not working properly can result in increased crop times and poor plant quality. Lela Kelly from Dosatron says some growers believe that, because the injector is sucking liquid and the stock tank isn’t as full, it must be functioning properly. This isn’t always true! It’s best to check your injector for accuracy and put it on a yearly maintenance program.

Just because your injector is sucking liquid and the stock tank isn’t as full, doesn't mean it's functioning properly.

To check the calibration of your fertilizer injector, start with a calibrated conductivity/EC meter and measure the conductivity of a clear water sample. Next, mix up a fertilizer stock solution to yield a 200-ppm nitrogen solution through the injector at 1:100. Turn the injector on and allow the fertilizer to flow through the hose for several minutes. Collect at least a quart of fertilizer solution to ensure a uniform sample,and use the conductivity/EC meter to measure the conductivity of that fertilizer solution.

Take this conductivity reading from the fertilizer and subtract the conductivity reading of the clear water to yield the true conductivity of the fertilizer solution. Compare the reading with the EC or conductivity reading for 200-ppm nitrogen on the fertilizer bag. If the conductivity reading is within 5-10% of the target EC or conductivity, your fertilizer injector is working properly. If this conductivity reading significantly deviates from the target, the injector isn’t working properly and should be repaired, re-built or replaced.

A physical calibration test can also be conducted by setting your Dosatron to 1:128, (1:128 = 1 ounce to 1 gallon of water). Fill a container with 5 ounces of fertilizer solution and place the Dosatron suction hose inside. Turn your Dosatron on so that it sucks up the 5 ounces. When the 5 ounces of fertilizer solution is gone, it should have yielded a 5-gallon bucket of fertilizer solution. This indicates that the injector is calibrated. If the injector doesn’t deliver enough fertilize, it’s an immediate indication that it’s time for a seal kit/component kit replacement.

Dosatron fertilizer injectors are powered by water pressure, using the flow of water in your irrigation system to drive a piston pump and using patented technology to deliver a precise dose of fertilizer or chemicals through the irrigation lines. It’s important to set up your injector system properly, using both a filter and a check valve. Dosatron recommends a 200-micron filter to keep all debris from effecting the action of the unit. A check valve is also important. “Back Flow” water can impact the unit with as much as four times the initial water pressure, and can cause severe damage to the injector.

Quick Steps to Maintain Your Dosatron Injector

    Dosatron Mini-Maintenance Kit
    Image courtesy of Dosatron
  1. Purchase a ‘Do It Yourself’ Mini-Maintenance Kit that includes the components and Dosa-Klean for your size Dosatron.
  2. Before and after Dosa-Klean
    Image courtesy of Dosatron
    The night prior to changing the maintenance kit, take apart your Dosatron and thoroughly rinse all parts in clean water to remove any chemicals.
  3. Dissolve one packet of Dosa-Klean into one gallon of water. Larger injector units may require two packets per two gallons of water.
  4. Soak overnight or up to 48 hours in the Dosa-Klean solution, then rinse thoroughly. Dosa-Klean will remove rust, mineral deposits and calcifications without scrubbing.
  5. Next, it’s important to install all of the new components included in the maintenance kit.
  6. Put the injector back together. If needed, Dosatron includes instructions with pictures to assist you.
  7. Finish by conducting another calibration test, to ensure everything is injecting properly.
Note: If your Dosatron is not clicking, this is not an issue that a seal kit/component kit will fix. It’s indicative of a motor problem, and you should call Dosatron’s Customer Service for assistance at 800-523-8499.
Product Description Item no.
Dosatron Mini-Maintenance Kit D14MZ2 14-GPM Unit 219-000
Dosatron Mini-Maintenance Kit D45RE15 20-GPM Unit 219-001
Dosatron Mini-Maintenance Kit D8R 40-GPM Unit 219-003
Dosatron Mini-Maintenance Kit D8RE2 40-GPM Unit 219-005
Dosatron Mini-Maintenance Kit D20S 100-GPM Unit 219-004
Dosatron Dosa-Klean Single-Use Packet -- 85 gms. 33-2633
Dosatron Dosa-Klean Economy Pail -- 3 lbs. 33-2636

In Defense of Cyclamen: How to Fight Off Foliar Diseases

As the weather begins the slow slide into the darker and more humid conditions of fall and winter, cyclamen crops require extra attention. Cyclamen benefit from the cooler temperatures after a summer of high temperature stress but, as the crop canopy fills in, the increase in humidity poses challenges. Specifically, foliar diseases can become more common at this stage of the crop.

Sierra Synchro cyclamen on the bench.
Photo courtesy of Syngenta Flowers.
Botrytis can gain a foothold during the fall and winter due to the dense plant canopy. Look for gray, fuzzy growth under the canopy. Under high disease pressure, petioles and developing flower stalks can be girdled near the corm. Flower damage shows as darkly pigmented areas or dark spotting on the petals. To help keep Botrytis at bay, remove senesced leaves and flowers, increase airflow and, to the extent possible, keep the relative humidity in check.

Overfertilization can predispose plants to foliar diseases, as well as crown and root rots. Keep close tabs on soil EC levels and leach if needed to keep EC levels below 1.25 via the saturated paste method. Many cyclamen growers rely on calcium nitrate and potassium nitrate as the backbone of their cyclamen fertilizer program. GGSPro has a bulletin on cyclamen production that provides detailed nutritional information. Fungicides are often needed to augment even the best cultural practices. Resistance is a significant issue when it comes to Botrytis,so take advantage of the chart at the end of this table that sorts effective fungicides by mode of action.

Cyclamen benefit from the cooler temperatures of fall and winter but, as the crop canopy fills in, foliar diseases can become more common at this stage of the crop.

Unfortunately, Botrytis isn’t the only foliar disease cyclamen growers need to prepare for. Two anthracnose diseases also affect cyclamen. The less serious Colletotrichum causes small brown spots on leaves. The more serious Gleosporium(Cryptocline) attacks young petioles, with distinctive drying and malformation of the young tissue. Gleosporium can also attack older tissue and flower buds, resulting in drying and distortion. The cultural techniques discussed for Botrytis will also be helpful here. In some cases, fungicides that control Botrytis are also effective against anthracnose diseases. Consult the table below for assistance in sorting through the available options.

Cyclamen displaying INSV symptoms
Viruses can produce distinct foliar symptoms that can be confused with other foliar problems. The thrips-transmitted tospoviruses, INSV and TMSV, both occur in cyclamen. Watch for ring spots, mosaic patterns, atypical leaf coloration (yellow, bronze or brown) and distortion. Should you discover any of these symptoms during your scouting efforts, discard effected plants immediately and work to control thrips. GGSPro can advise regarding biocontrol options, as well as insecticides that have shown good plant safety on cyclamen.

Always read and follow the pesticide label. Products other than those mentioned may also be safe and effective.

ProductDescriptionMode of ActionBotrytisAnthracnoseItem no.
Affirm WDG 0.5 lb. 19 X X 71-1129
Camelot O* 1 gal. M1 X 70-21202
Cease 1 gal. 44 X X 71-13301
Daconil Ultrex* 5 lbs. M5 X X 71-1420
Emblem 1 pt. 12 X X 71-1570
Medallion WDG 8 oz. 12 X X 71-16502
Mural WDG 1 lb. 7&11 X X 71-1690
Nordox 75 WG** 12.5 lbs. M1 X 71-1700
Orkestra Intrinsic* 16 oz. 7&11 X X 71-2200
Pageant Intrinsic WG 1 lb. 7&11 X X 71-26801
Palladium WDG 2 lbs. 9&12 X X 71-2685
Phyton 35* 1 gal. M1 X 71-2737
Protect DF** 6 lbs. M3 X 71-2748
Trigo 1 lb. 3&11 X X Coming Soon
Triathlon BA 1 gal. 44 X X 71-3040
* Cyclamen bloom safety unknown
** Residue may be noticeable

Managing the 3 Ms of Poinsettias: Manganese, Molybdenum and Magnesium

The pH of soilless media plays a large role in the availability of nutrients to plants. Most micronutrients tend to be more available to plants at low media pH. For crops inefficient at uptake of micronutrients, pH above 6.0 may result in micronutrient deficiencies. For crops efficient at micronutrient uptake, such as poinsettias, pH below 5.8 can cause micronutrient toxicities.

Some crops and nutrients are more affected by media pH than others. Poinsettias and the nutrients Iron (Fe), manganese (Mn) and molybdenum (Mo) are good examples. Fe and Mn are more available to plants as the pH drops below 6.2. Molybdenum and poinsettias present an opposite situation. Molybdenum is more available at higher pH.

To avoid a combined problem of reduced availability and low uptake, it’s essential to maintain poinsettias at a soil pH in the range of 6.0-6.5.

Nutrients can be classified according to how mobile they are within the plant. The differences in nutrient mobility lead to differences in symptom expression, which can be recognized and used for diagnosis of nutrient deficiency or toxicity. Nutrients are classified as: mobile, immobile or intermediate.

  1. Mobile nutrients move easily within the plant. The lower leaves are able to give up these nutrients to supply the younger leaves. Therefore, deficiency symptoms first express on the lower leaves of the plant. Mobile nutrients include nitrogen (N), phosphorus (P), potassium (K) and magnesium (Mg). 
  2. Immobile nutrients don’t move easily through the plant. The lower leaves are unable to supply nutrients to the younger foliage. Deficiency symptoms first express on the youngest leaves. Immobile nutrients include boron (B), calcium (Ca), copper (Cu), iron (Fe), manganese (Mn) and zinc (Zn).
  3. With intermediate mobility, early deficiency symptoms can occur anywhere on the plant. Somewhat mobile nutrients include molybdenum (Mo) and sulfur (S). 

Manganese (Mn) Deficiency

Manganese deficiency
Poinsettias with manganese deficiency exhibit symptoms including interveinal chlorosis starting with the youngest growth. The veins will appear sunken while the tissue between the veins looks raised. Frequent media analysis should be conducted to treat before symptoms appear. Maintain media pH below 6.2 to improve manganese availability.

Mn symptoms can be easily confused with iron deficiency. To distinguish from an iron deficiency, look for the characteristic change in leaf texture to a corrugated look, sometimes similar to an orange peel in appearance—that’s typical of manganese. High levels of iron in the media inhibit the uptake of manganese. If media tests confirm a deficiency, apply a corrective drench of chelated manganese at 1.0-1.5 oz per 100 gal. Retest the media before making additional applications.

Molybdenum (Mo) Deficiency

Molybdenum deficiency
Poinsettias have a unique requirement for molybdenum and are produced at a higher media pH to accommodate this need. Molybdenum becomes more available as soil pH rises above 6.0. Growers incorporate poinsettia feeds with molybdenum as a part of the fertilizer regime, but they often have to supplement with additional ammonium molybdate. This is especially true when using standard peat-lite fertilizers. Some of the newer poinsettia cultivars appear to have higher Mo requirements. If you’re not using a fertilizer specifically for poinsettias with elevated Mo, or soil tests indicate Mo is lacking, you can make pulse treatments or opt for a constant injection plan, both of which are explained in a bulletin from GGSPro titled, “Molybdenum Applications for Poinsettias.”

Molybdenum deficiencies are slow to express and should be treated preventatively in the months of September and October. Marginal leaf yellowing and cupping with leaf scorch distorted symptoms usually occur in the mid-region of the foliage right below the bracts. Molybdenum applications made after the symptoms appear, unfortunately, won’t reverse these symptoms. Large, well-formed bracts will often hide those symptoms. Growers experiencing low soil pH may have to rely on a foliar spray instead of a soil drench, although correcting the soil pH is recommended.

Magnesium (Mg) Deficiency

Magnesium deficiency
Magnesium deficiency symptoms begin with an overall diminished green foliage color. Left untreated, symptoms progress to interveinal chlorosis first appearing on the lowest leaves. Downward cupping and a thicker texture may also occur with more severe deficiencies. Magnesium deficiency is often an indication that the overall fertility level of the crop is too low.

Apply magnesium as a one-time corrective drench application or as a part of a constant liquid feed program. Epsom salts are an inexpensive option to provide magnesium, and can be added to most fertilizers with the exception of those containing calcium (e.g., 15-0-15, 13-2-13). The one-time corrective rate for Epsom salts is 8 oz per 100 gal. Constant injection of Epsom salts can be done at lower rates, generally 2-3 oz per 100 gal based on the amount of magnesium in the irrigation water, including the fertilizer.

ProductDescriptionItem No
Chelated manganese1 lb.91-2193
Ammonium molybdate1 lb.91-2198
Magnesium sulfate/Epsom salts55 lbs.14MGSUL55

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